Uplink scheduling apparatus and method based on uplink report in wireless communication system

Abstract

A method and an apparatus for scheduling uplink transmissions according to a maximum transmission power and power Headrooms (PHs) reported by a User Equipment (UE) are provided. A method for reporting the PHs for carriers used by a terminal in a mobile communication system supporting carrier aggregation includes generating a message including the PHs along with indicators indicating whether a real transmission is scheduled on an uplink data channel of corresponding carrier, and including, when the real transmission is scheduled, a maximum transmission power used for calculating the PHs in the generated message.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser. No. 15/278,524, filed on Sep. 28, 2016, which is a continuation application of prior U.S. application Ser. No. 13/288,305, filed on Nov. 3, 2011, which has issued as U.S. Pat. No. 9,461,805 on Oct. 4, 2016 and claimed the benefit under 35 U.S.C. § 119(a) of a Korean patent application filed on Nov. 5, 2010 in the Korean Intellectual Property Office and assigned Serial No. 10-2010-0109664, and of a Korean patent application filed on Nov. 23, 2010 in the Korean Intellectual Property Office and assigned Serial number 10-2010-0116958, the entire disclosure of each of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to mobile communications. More particularly, the present invention relates to a method and apparatus for scheduling uplink transmissions based on a maximum transmission power and a power headroom reported by a User Equipment (UE).

2. Description of the Related Art

Mobile communication systems have been developed to provide subscribers with voice communication services while on the move using wireless communication services. With the rapid advancement of technologies, the mobile communication systems have evolved to support high speed data communication services as well as the standard voice communication services.

Recently, the next generation mobile communication system of the 3rd Generation Partnership Project (3GPP), Long Term Evolution (LTE) system is being developed. The LTE system realizes high-speed packet-based communication at about 100 Mbps. Regarding commercialization of the LTE system, a discussion is being held regarding two schemes of the LTE system: one scheme for reducing a number of nodes located in a communication path by simplifying a configuration of a network, and another scheme for maximally approximating wireless protocols to wireless channels.

Unlike voice service, in providing data service a resource is allocated according to an amount of data to be transmitted and a channel condition. Accordingly, in the wireless communication system, such as a cellular communication system, a scheduler manages resource allocation in consideration of the resource amount, the channel condition, and the amount of data to be transmitted. This is also the case in the LTE system as one of the next generation mobile communication systems such that the scheduler located in a base station manages and allocates the radio resources used by the LTE system.

Typically, the UE transmits scheduling information to an evolved Node B (eNB) for uplink scheduling in the LTE system. The scheduling information includes a Buffer Status Report (BSR) and a Power Headroom Report (PHR). The PHR is used, when the eNB assigns resources the UE, to limit the transmit power of the UE to a maxim transmission power. If the PHR is not accurate, it is difficult for the eNB to assign and schedule resources effectively and the inaccurate PHR may cause interference with other transmissions and thus it is beneficial for the eNB to have the ability to precisely interpret the PHR reported by the UE.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method, apparatus, and system for processing the scheduling information efficiently in a mobile communication system.

Another aspect of the present invention is to provide a method, apparatus, and system for processing the scheduling information between a User Equipment (UE) and an evolved NodeB (eNB) efficiently.

Another aspect of the present invention is to provide a method, apparatus, and system for reporting power headroom and maximum transmission power of a UE efficiently in a mobile communication system.

In accordance with an aspect of the present invention, a method for reporting Power Headrooms (PHs) for carriers of a terminal in a mobile communication system supporting carrier aggregation is provided. The method includes containing the PHs with indicators in an extended Power Headroom Report (PHR), the indicator indicating whether the PH is based on a real transmission on an uplink data channel, and containing, if the PH is based on the real transmission on the uplink data channel, a maximum transmission power used for calculation of the PH in the extended PHR.

In accordance with another aspect of the present invention, an apparatus for reporting Power Headrooms (PHs) for carriers used by a terminal in a mobile communication system supporting carrier aggregation is provided. The apparatus includes a power calculator for calculating the PHs, and a controller for containing the PHs with indicators in an extended Power Headroom Report (PHR), the indicator indicating whether the PH is based on a real transmission on an uplink data channel, and for containing, if the PH is based on the real transmission on the uplink data channel, a maximum transmission power used for calculation of the PH in the extended PHR.

In accordance with another aspect of the present invention, a method for receiving Power Headrooms (PHs) for carriers of a base station in a mobile communication system supporting carrier aggregation is provided. The method includes determining the PHs with indicators in an extended Power Headroom Report (PHR), the indicator indicating whether the PH is based on a real transmission on an uplink data channel, and determining, if the PH is based on the real transmission on uplink data channel, a maximum transmission power used for calculation of the PH in the extended PHR.

In accordance with still another aspect of the present invention, an apparatus for receiving Power Headrooms (PHs) for carriers of a base station in a mobile communication system supporting carrier aggregation is provided. The apparatus includes a controller for determining the PHs with indicators in an extended Power Headroom Report (PHR), the indicator indicating whether the PH is based on a real transmission on an uplink data channel, and for determining, if the PH is based on the real transmission on uplink data channel, a maximum transmission power used for calculation of the PH in the extended PHR, and a scheduler for scheduling the uplink data channel according to the PHs and maximum transmission powers.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an architecture of a mobile communication system according to an exemplary embodiment of the present invention;

FIG. 2 is a diagram illustrating a protocol stack of a mobile communication system according to an exemplary embodiment of the present invention;

FIG. 3 is a diagram illustrating an exemplary situation of carrier aggregation in a mobile communication system according to an exemplary embodiment of the present invention;

FIG. 4 is a diagram illustrating formats of payload of Power Headroom Report (PHR) Medium Access Control (MAC) Control Element (CE) according to an exemplary embodiment of the present invention;

FIG. 5 is a diagram illustrating an exemplary information format for reporting a Power Headroom (PH) and P_CMAX according to an exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a User Equipment (UE) procedure for uplink scheduling method according to an exemplary embodiment of the present invention;

FIG. 7 is a flowchart illustrating an evolved Node B (eNB) procedure for uplink scheduling method according to an exemplary embodiment of present invention;

FIG. 8 is a block diagram illustrating a configuration of a UE according to an exemplary embodiment of the present invention;

FIG. 9 is a block diagram illustrating a configuration of an eNB according to an exemplary embodiment of the present invention;

FIG. 10 is a diagram illustrating a configuration of a PHR MAC CE for use in an uplink scheduling method according to an exemplary embodiment of the present invention;

FIG. 11 is a signaling diagram illustrating uplink signaling procedure between a UE and an eNB according to an exemplary embodiment of the present invention; and

FIG. 12 is a flowchart illustrating a UE procedure for uplink scheduling method according to the second exemplary embodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

Exemplary embodiments of the present invention relate to a method and apparatus for a User Equipment (UE), which may also be referred to as a terminal, to report its Power Headroom (PH) to facilitate uplink transmission through multiple uplink carriers in a mobile communication system supporting carrier aggregation. Particularly, exemplary embodiments of the present invention propose a method and apparatus for reporting the maximum transmission power and headroom of the UE while minimizing overhead.

FIG. 1 is a diagram illustrating an architecture of a mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a radio access network of the mobile communication system includes evolved Node Bs (eNBs) 105, 110, 115, and 120, a Mobility Management Entity (MME) 125, and a Serving-Gateway (S-GW) 130. The User Equipment (UE) 135, which may also be referred to as a terminal, connects to an external network via the eNBs 105, 110, 115, and 120 and the S-GW 130.

The eNBs 105, 110, 115, and 120 correspond to legacy node Bs of a Universal Mobile Telecommunications System (UMTS). The eNBs 105, 110, 115, and 120 allow the UE to establish a radio link and are responsible for more complicated functions, as compared to the legacy node B. In the LTE system, all the user traffic, including real time services such as Voice over Internet Protocol (VoIP), are provided through a shared channel Thus there is a need for a device which is located in the eNB for scheduling data according to state information of the UEs.

In order to secure a data rate of up to 100 Mbps, the Long Term Evolution (LTE) system adopts Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology. Also, the LTE system adopts Adaptive Modulation and Coding (AMC) to determine a modulation scheme and a channel coding rate in adaptation to the channel condition of the UE. S-GW 130 is an entity for providing data bearers so as to establish and release data bearers under the control of the MME 125. MME 125 provides various control functions and is connected to a plurality of eNBs 105, 110, 115, and 120.

FIG. 2 is a diagram illustrating a protocol stack of a mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the protocol stack of the mobile communication system, which is an LTE system, includes Packet Data Convergence Protocol (PDCP) layer 205 and 240, Radio Link Control (RLC) layer 210 and 235, Medium Access Control (MAC) layer 215 and 230, and Physical (PHY) layer 220 and 225. The PDCP layer 205 and 240 is responsible for Internet Protocol (IP) header compression/decompression. The RLC layer 210 and 235 is responsible for segmenting a PDCP Protocol Data Unit (PDU) into segments of appropriate size for Automatic Repeat Request (ARQ) operations. The MAC layer 215 and 230 is responsible for establishing a connection to a plurality of RLC entities so as to multiplex the RLC PDUs into MAC PDUs and demultiplex the MAC PDUs into RLC PDUs. The PHY layer 220 and 225 performs channel coding on the MAC PDU and modulates the MAC PDU into OFDM symbols in order to transmit the OFDM symbols over a radio channel or performs demodulating and channel-decoding on received OFDM symbols and delivers the decoded data to a higher layer.

FIG. 3 is a diagram illustrating an exemplary situation of carrier aggregation in a mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, typically an eNB can use multiple carriers for transmitting and receiving in different frequency bands. For example, an eNB 305 can be configured to use a carrier 315 with a center frequency f1 and a carrier 310 with a center frequency f3. If carrier aggregation is not supported, a UE 330 has to transmit/receive data using only one of the carriers 310 and 315. However, the UE 330 having the carrier aggregation capability can transmit/receive data using both the carriers 310 and 315.

An eNB can increase an amount of resources allocated to a UE having the carrier aggregation capability according to a channel condition of the UE so as to improve a data rate of the UE. In a case where a cell is configured with one downlink carrier and one uplink carrier, the carrier aggregation can be understood to be as if the UE communicates data via multiple cells. With the use of carrier aggregation, the maximum data rate increases in proportion to the number of aggregated carriers.

In the following description of the present exemplary embodiments, the phrase “the UE receives data through a certain downlink carrier or transmits data through a certain uplink carrier” means that the UE transmits or receives data through control and data channels provided in a cell corresponding to center frequencies and frequency bands of the downlink and uplink carriers. Although the description of the present exemplary embodiments is directed to an LTE mobile communication system, the present invention is not limited thereto and can be applied to other similar types of wireless communication systems supporting carrier aggregation.

When a UE uses a plurality of aggregated carriers, such a case may be understood as the UE having a plurality of serving cells. A cell or a service cell can be configured with downlink and uplink resources, and the uplink resource can exist depending on an uplink design. The service cells are categorized into Primary Cell (PCell) and Secondary Cell (SCell). The PCell is a cell that is always in an active state, and the SCell is a cell that is in one of the active and an inactive state under the control of the eNB. If a SCell is in the inactive state, then there is no data transmission/reception through the cell. In this case, the UE turns off the power to the parts related to the serving cell in inactive state in order to save power consumption. In the following descriptions of the exemplary embodiments, the term “cell” is used interchangeably with the term “serving cell.”

In the LTE mobile communication system, in order to prevent the uplink transmission from interfering with transmissions in other frequency bands, the uplink transmission power is limited to an appropriate level. That is, spurious emissions, which are unintended transmissions on radio frequencies, should be reduced in order to fulfill a Spurious Emission Requirement. For this purpose, the UE calculates uplink transmission power with a predetermined function and performs an uplink transmission at the calculated uplink transmission power. For example, the UE calculates a request uplink transmission power value by inputting parameters, such as scheduling information, an allocated resource amount, a Modulation and Coding Scheme (MCS), and path loss, for estimating a status or a condition of a channel, and then performs the uplink transmission using the calculated request uplink transmission power value. The uplink transmission power of the UE is limited to the maximum transmission power of the UE and, if the calculated transmission power is greater than the maximum transmission power of the UE, the UE performs the uplink transmission with the maximum transmission power rather than the calculated transmission power. In this case, since the uplink transmission is performed with a power less than the calculated transmission power, a degradation of uplink transmission quality may result.

Accordingly, in order to avoid the degradation of the uplink transmission quality, the eNB performs scheduling such that the requested transmission power does not exceed the maximum transmission power. However, some parameters such as path loss cannot be determined by the eNB, and thus, the UE provides a report on its Power Headroom (PH) to the eNB by transmitting a Power Headroom Report (PHR) message. The PH is the difference between the maximum transmission power (P_CMAX) and the requested uplink transmission power, which will be also referred to as a Physical Uplink Shared Channel (PUSCH) transmission power. P_CMAX is a variable and determined by the UE according to the following equations and description.

P_CMAX is a value selected between a minimum value and a maximum value as shown in formula (1):
P_{CMAX_L}≤P_CMAX≤P_{CMAX_H}  (1)

In formula (1), P_{CMAX_L} and P_{CMAX_H} are calculated by equations (2) and (3):
P_{CMAX_L}=MIN {P_EMAX−ΔT_C, P_PowerClass−MPR−A-MRP−ΔT_C}  (2),
P_{CMAX_H}=MIN {P_EMAX, P_PowerClass}  (3)
where P_EMAX, ΔT_C, P_PowerClass, MPR, and A-MRP are specified in 3GPP Technical Specification (TS) 36.101 and can be summarized as follows. P_EMAX denotes the maximum allowed UE output power in the current cell, as determined by the eNB. P_PowerClass indicates a power class of the UE that denotes the maximum transmission power determined by physical properties of the UE. The power class of the UE is determined at the manufacturing stage, and the UE notifies the eNB of the power class through RRC signaling.

MPR, A-MPR, and ΔT_C are the parameters defining the threshold value that is used for adjusting the maximum transmission power in order to meet the predetermined spurious emission requirements. MPR is a value determined by the resource amount allocated to the UE (i.e., an amount of bandwidth allocated to the UE) and a modulation scheme. The value of MPR depends on an amount of a transmission resource and a modulation scheme, which are specified in table 6.2.3-1 of the 3GPP TS 36.101. A-MPR is a value determined by a frequency band used for uplink transmission, local characteristics, and an uplink bandwidth, and is defined in tables 6.2.4-1, 6.2.4-2, and 6.2.4-3 of the 3GPP TS 36.101. A-MPR is used for a frequency band that may be particularly sensitive to adjacent spurious emissions due to the local characteristics and frequency band characteristics. ΔT_C is the parameter for allowing additional transmission power adjustment in a case where uplink transmissions are at a frequency band edge. If the uplink transmission is performed in the lowest 4 MHz or the highest 4 MHz of a bandwidth of a certain frequency band, then the UE sets ΔT_C to 1.5 dB and, otherwise, sets ΔT_C to 0.

As shown in formula (1), since P_CMAX is a value that the UE can set randomly between a maximum value and a minimum value, it may not be enough for the eNB to make scheduling decision only with the PH. For example, the UE reports a PH calculated with the P_CMAX set to X, but if the eNB misinterprets the P_CMAX as Y, then the scheduling decision will be made incorrectly. The problem of the incorrect scheduling decision can be worse when the eNB performs scheduling for a multicarrier transmission of the UE. Unlike the single carrier transmission, in which the eNB can allocate additional transmission power to the UE using the PH reported by the UE in spite of an incorrect P_CMAX, the eNB cannot calculate the PUSCH transmission power from the PH since the PH is just the difference between the unknown P_CMAX and the PUSCH transmission power. The eNB cannot determine a total transmission power in a multicarrier transmission in a state where the PUSCH transmission powers of individual cells are not known. Accordingly, in order to perform scheduling for the multicarrier uplink transmissions, the eNB is provided and uses the P_CMAX as well as the PH.

In order to address the above problem, the present exemplary embodiments of the present invention provide a method for reporting the P_CMAX along with the PH, wherein the P_CMAX is used to calculate the PH. Since the P_CMAX is reported so as to allow the eNB to interpret the PH correctly, it is of little use to transmit or report only the P_CMAX. Transmitting or reporting only the P_CMAX also has a drawback in that a new MAC Control Element (CE) for transmitting control information of the MAC layer should be defined. In order to overcome this problem, the exemplary embodiments of the present invention provide a method for reporting the P_CMAX in a PHR MAC CE. Also, in order to reduce the overhead for processing the P_CMAX report, the UE reports the P_CMAX only when a predetermined condition is fulfilled.

That is, the P_CMAX is transmitted to the cells in which PHs are reported via the PHR only when the eNB cannot infer the P_CMAX. For example, there can be a case where the same P_CMAX is configured in several cells and, in this case, the P_CMAX is reported to only one of these cells. The same P_CMAX can be set in the multiple cells when the cells are operating in the same frequency band. In this case, the same maximum transmission power reductions (MPR, A-MPR, and ΔT_C) are applied, the same P_CMAX is set for the cells. In the cells having no actual PUSCH transmission, the same P_CMAX is applied for reasons to be described later.

Here, the PH is the difference between the P_CMAX and the PUSCH transmission power. Accordingly, the PH for the cell having no PUSCH transmission is not calculated. However, since the eNB may schedule a PUSCH transmission in a cell that has no PUSCH transmission currently to occur in the near future, it is necessary to report the PH for the cell having no PUSCH transmission currently. In the exemplary embodiments of the present invention, the PH for the cell having no current PUSCH transmission is calculated using a predetermined transmission format. Since the purpose of the PH report for the cell having no current PUSCH transmission is to trace a variation of a path loss of the cell or a variation of accumulated values of transmission power control commands, the P_CMAX is less important in such a case. In the exemplary embodiments of the present invention, the P_CMAX of the cell having no current PUSCH transmission is a predetermined value, and thus, is not transmitted and is not determined according to a P_CMAX report for the cells, thereby reducing overhead of the eNB.

In the exemplary embodiments of the present invention, one of two reserved bits of the PH, the reserved bit being referred to as a P bit, is used for the P_CMAX report in a certain cell in order to indicate whether the P_CMAX is reported or not. The other bit of the two reserved bits, the other bit being referred to as an V bit, is used to indicate whether the PH is calculated based on the actual PUSCH transmission.

FIG. 4 is a diagram illustrating formats of payload of extended PHR MAC CE according to the first exemplary embodiment of the present invention.

Referring to FIG. 4, the PHR includes PH information 415 and P_CMAX information 420 for a plurality of cells. The PH information 415 and P_CMAX information 420 for one cell can be disposed at a distance from each other in the payload, as shown in Format 1, or may be disposed adjacent to each other in the payload, as shown in Format 2. In the PH information 415 for a certain cell, a P bit 405 indicates whether the PHR includes a P_CMAX for the corresponding cell, and an V bit 410 indicates whether the PH information 415 is calculated based on the actual PUSCH transmission. The P bit 405 being set to 0 indicates that the PHR includes the P_CMAX for the corresponding cell, and the P_CMAX information 420 can be arranged at an appropriate position in the payload according to an arrangement order of the cells, as shown in Format 1. Alternatively, the information P_CMAX 420 can be disposed to be right after the PH information of the corresponding cell, as shown in Format 2. If the P bit 405 is set to 1, this indicates that the PHR includes no P_CMAX for the corresponding cell and the P_CMAX for the corresponding cell is set to a predetermined value, for example, the V bit 410 is set to 1, and is identical with the P_CMAX of other cells. In other words, the PH information 415 is not associated with actual PUSCH transmission and thus a predetermined value of P_CMAX is used.

FIG. 5 is a diagram illustrating an exemplary information format for reporting a PH and a P_CMAX according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the PHR includes the PH information for a PCell, a SCell 1, a SCell 2, a SCell 3, and a SCell 4. For the purpose of convenience, the PHR of FIG. 5 is depicted in Format 1 of FIG. 4. Here, the SCell 3 does not include a PUSCH transmission, and the other cells include PUSCH transmissions. The P_CMAX of the SCell 1 is equal to the P_CMAX of the PCell, and the P_CMAX of the SCell 2 is equal to the P_CMAX of the S Cell 4. Here, the PH information is arranged such that the PH information of the PCell is followed by the PH information of the SCells in a sequential manner That is, the PH information is arranged according to an order of PCell, SCell 1, SCell 2, SCell 3, and SCell 4. The P_CMAX is transmitted in the cell at the start of the list or in the cell having the lowest cell index from among the cells for which the same P_CMAX is set. That is, from among the PCell, the SCell 1, the SCell 2, the SCell 3, and the SCell 4, the P_CMAX is transmitted in the PCell and the SCell 1.

That is, the UE sets the P bits to be 0 for the PH information for the cells in which the P_CMAX is reported, and sets the P bits to be 1 for the PH information for the rest of the cells. For the cells in which P_CMAX is not reported, P_CMAX information 515 and 525 for the cells in which the PHs are calculated according to the actual PUSCH transmission (i.e., the SCell 1 and the SCell 2) are equal to the P_CMAX information 505 and 510. The P_CMAX information 505 and 510 is for the cells for which the PHs are arranged prior to the cells in which P_CMAX information are reported, and are the closest cells or cells that have a low cell index and are closest, i.e., the P_CMAX information 505 and 510 of the PCell and SCell. In a case of the SCell 1, since the PCell fulfills the above described conditions for the cells in which P_CMAX is reported (i.e., the cell index of the PCell is 0), the P_CMAX 515 of the SCell 1 is equal to the P_CMAX 505 of the PCell. Likewise, the P_CMAX 525 of the SCell 4 is equal to the P_CMAX 510 of the SCell 2. Among the cells in which the P_CMAX is not reported, such as the cell for which the PH is calculated according to the virtual transmission format other than actual PUSCH transmission, i.e., the SCell 3, which is the cell with V bit set to 1, the P_CMAX 520 is set to a predetermined value. The predetermined value can be P_{CMAX_H}.

Although, as shown in FIGS. 4 and 5, it is assumed that the size of the P_CMAX information is 5 bits or 6 bits, the present invention is not limited thereto, and the size of the P_CMAX information can be greater than or less than 5 bits. The P_CMAX information can be expressed in a format indicating the maximum value of P_CMAX , i.e., the power reduction in P_{CMAX_H}. For example, the index of P_CMAX is set to 0 for indicating that the P_CMAX equal to P_{CMAX_H} or is set to 1 for indicating a value that is reduced by as much as 1 dB from the P_{CMAX_H}. In this case, it is possible, with 5 bits, to express the P_CMAX obtained by a reduction of up to as much as 31 dB from the P_{CMAX_}H, and 5 bits can be an appropriate length for the size of the P_CMAX information in consideration of there being a high probability of no power reduction over 31 dB. One of three reserved bits 530 of the P_CMAX information can be used to indicate that a larger power reduction is applied to the P_CMAX due to the simultaneous transmission of another radio technology. If another radio technology, e.g., a CDMA2000 system, is used simultaneously along with the LTE system, then the transmission power of the LTE system can be further limited with a notification sent to the eNB scheduler, such that the eNB can perform scheduling efficiently.

FIG. 6 is a flowchart illustrating a UE procedure for uplink scheduling method according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the UE configures a Release-10 (REL-10) PHR function in step 605. The REL-10 PHR function differs from the Release-8 (REL-8) PHR function as per a format and a type of information reported. The REL-10 PHR function can be configured through RRC control message signaling for activation of REL-10 techniques, such as carrier aggregation. After step 605, the UE waits until PHR generation conditions are fulfilled while performing a predetermined operation. The PHR generation conditions are fulfilled when there are transmission resources available for a new uplink transmission, a timer restricting PHR transmission has expired (or is currently running), and the path loss of at least one cell, from among the cells fulfilling a predetermined condition, is changed so as to be over a predetermined threshold value. Here, the cell fulfilling the predetermined condition can be the cell reporting the power headroom from among the cells in an active state, e.g., the cell for which uplink resource is configured.

If the PHR generation conditions are fulfilled, or met, at step 610, then the UE triggers a PHR process for reporting PHs for the cells configured with uplink resources from among the currently active cells in step 615. Next, the UE calculates PUSCH transmission powers for the PHR-triggered cells or for cells for which PHs are reported, using equation (4) in step 620:
PUSCH power=10log₁₀(M_PUSCH(i))+P_{O_PUSCH}(j)+α(j)·PL+Δ_TF(i)+f(i)  (4)
where M_PUSCH(i) denotes a value determined by a number of assigned transmission resources, P_{O_PUSCH}(j) denotes the sum of the offsets defined per cell and the offsets defined per UE, PL denotes the path loss, α(j) denotes the coefficient defined per cell and multiplied with the path loss, Δ_TF(i) denotes the value determined by MSC level, and f(i) denotes the accumulated value of Transmission Power Control (TPC) command Further discussion of the variable discussed above with respect to equation (4) may be found in the 3GPP TS 36.213.

When calculating the PH for the cell in which the PUSCH is transmitted in a subframe carrying the PHR, the value for the actual PUSCH transmission is the PUSCH transmission parameter, which is the number of scheduled transmission resource blocks and a MCS level. In equation (4), the PL refers to the path loss of downlink resources of the cell in association with the uplink resources of the cell for which PH is calculated, and the f(i) refers to the accumulated value of the TPC command related to the PUSCH transmission of the cell for which PH is calculated.

Meanwhile, when calculating the PH of the cell having no PUSCH transmission in the subframe carrying the PHR, a predetermined value is used as the PUSCH transmission parameter. For example, both the 10log₁₀ and Δ_TF(i) can be set to be 0. The PL and the f(i) are set in a manner similar to the case where the PUSCH transmission exists in the subframe carrying the PHR. For the purpose of convenience, the method for calculating the PH of the cell having the PUSCH transmission in the subframe carrying the PHR is referred to as a PH calculation scheme 1, and the method for calculating the PH of the cell having no PUSCH transmission in the subframe carrying PHR is referred to as a PH calculation scheme 2.

Next, the UE determines a P_CMAX for each cell in which the PH is reported in step 625. As described above, the UE sets the P_CMAX for the cell having no transmission in the subframe carrying the PHR to a predetermined value. The UE determines the P_CMAX such that the PUSCH transmission power fulfills the spurious emission requirement for the cell having a transmission in the subframe carrying the PHR.

Next, in step 630, the UE calculates the PHs for the cells that are PHR-triggered or for the cells for which PHs are reported. The PH is the difference between the P_CMAX determined at step 625 and the PUSCH transmission power calculated at step 620. Next, the UE determines the arrangement order of the PHs for the cells in the payload of the PHR MAC CE in step 635. For example, the UE can arrange the PHs in ascending order according to the cell index. Next, the UE determines the cells for which the P_CMAX is reported and the cells for which no P_CMAX information is reported from among the cells for which PH is reported. At this time, the UE always reports the P_CMAX for the PCell and reports the P_CMAX for the rest cells only when the following conditions are not met. The below conditions are referred to as P_CMAX report skip conditions.

The first P_CMAX report skip condition is to skip the P_CMAX report when the P_CMAX of a certain cell is equal to the P_CMAX of the cell proceeding the current cell in the PH reporting order from among the cells for which P_CMAX is reported, or, otherwise, to perform the P_CMAX report. The second P_CMAX report skip condition is to skip the P_CMAX report when the PH of a certain cell is calculated with the PH calculation scheme 1 and, otherwise, to perform the P_CMAX report when the PH is calculated with the PH calculation scheme 2. The third P_CMAX report skip condition is to skip the P_CMAX report when one of the first and second P_CMAX report skip conditions is fulfilled and to perform the P_CMAX report when both the first and second P_CMAX report skip conditions are not fulfilled. The fourth P_CMAX report skip condition is to skip the P_CMAX report when the PH of a certain cell is calculated with the PH calculation scheme 2 or the P_CMAX for the corresponding cell is equal to the most recently reported P_CMAX for the same cell, and to perform the P_CMAX report when the PH of a certain cell is calculated with the PH calculation scheme 1 and the P_CMAX for the corresponding cell is different from the most recently reported P_CMAX for the same cell. According to the above conditions, it is determined, in step 640, for which cells the P_CMAX is reported.

Next, the UE sets the P bit of each cell's PH to an appropriate value in step 645. For example, if the P_CMAX is reported for the corresponding cell, the UE sets the P bit to 0 and, otherwise, if the P_CMAX is not reported for the corresponding cell, the UE sets the P bit to 1. The UE also sets the V bit to an appropriate value in each cell. For example, if the PH for the corresponding cell is calculated with the PH calculation scheme 1, then the UE sets the V bit of each cell's PH to 0 and, otherwise if the PH for the corresponding cell is calculated with the PH calculation scheme 2, then the UE sets the V bit of each cell's PH to 1.

Next, in step 650, the UE arranges the PHs for the individual cells in the payload of the PHR in the order determined at step 635. Next, in step 655, the UE arranges the P_CMAX information in the payload of the PHR in the PH arrangement order for the cells for which the P_CMAX report is determined. Finally, the UE generates a MAC sub header of the PHR MAC CE and transmits a MAC PDU encapsulating the MAC sub header and payload in step 660.

FIG. 7 is a flowchart illustrating an eNB procedure for an uplink scheduling method according to an exemplary embodiment of present invention.

Referring to FIG. 7, if a PHR MAC CE is received from the UE in step 705, then the eNB determines whether the PHR MAC CE is a REL-8 PHR MAC CE or REL-10 PHR MAC CE in step 710. If the PHR MAC CE is a REL-8 PHR MAC CE, then the eNB interprets the PH information included in the PHR MAC CE and schedules the UE in consideration of the PH so as to not cause a transmission power shortage problem in step 715. Otherwise, in step 720, if the PHR MAC CE is a REL-10 PHR MAC CE, then the eNB determines the P_CMAX of the cells whose P_CMAX is reported explicitly in the PHR MAC CE, i.e., the cells for which the P bit of the PH is set to 0. Next, in step 725, the eNB determines the P_CMAX of the cell whose P_CMAX is not reported in the PHR MAC CE, i.e., the cells for which the P bit of PH is set to 1.

At this time, from among the cells whose P_CMAX is explicitly reported, the eNB determines the P_CMAX of the cell preceding and closest to the cell for which the V bit is set to 0 in the PHR to be the P_CMAX of the corresponding cell. The eNB also determines a predetermined P_CMAX , e.g., P_{CMAX_H}, for the cell for which the V bit is set to 1 as being the P_CMAX of the corresponding cell. Next, in step 730, the eNB interprets the PH information included in the PHR MAC CE and schedules the UE in consideration of the PH information and the P_CMAX information so as to not cause a transmission power shortage.

Furthermore, the present exemplary embodiment of the present invention can be simplified such that, when the P_CMAX information for the cells for which the P bit is not used and the V bit is set to 0 from among the cells for which the PH and one P_CMAX is reported. Alternatively, individual P_CMAX information for the cells for which the V bit is set to 0 are transmitted separately.

With respect to the UE, the simplified UE procedure is identical to that as depicted in FIG. 6 except for the following features. That is, the UE determines the cells for which P_CMAX information is reported and the cells for which P_CMAX information is not reported from among the cells for which PHs are reported. The UE does not report the P_CMAX for the cells for which PHs are calculated using the PH calculation scheme 2, which are the cells having no uplink transmission or the cells using a predetermined format for calculating the PUSCH transmission power. The UE checks the P_CMAX of the cells for which the PHs are calculated using the PH calculation scheme 1, which are the cells having an uplink transmission, i.e., the cells using the transmission format actually used for calculating the PUSCH transmission power. If the P_CMAX information of all the cells are identical with each other, then the UE determines to include one P_CMAX . Accordingly, it is determined to report only the P_CMAX of the PCell. If the P_CMAX for at least one cell differs from the P_CMAX for other cells, then it is determined to report P_CMAX information for the respective cells that are calculated using the PH calculation scheme 1.

Referring to FIG. 6, in step 645, the UE sets the V bit to an appropriate value. For example, the V bit is set to 0 when the PH of the corresponding cell is calculated using the PH calculation scheme 1, and the V bit is set to 1 when the PH of the corresponding cell is calculated using the PH calculation scheme 2. In a case of using the simplified UE procedure, the P bit is not necessary. This is because the length of the PHR payload is indicated explicitly by an L field and, thus, the eNB can determine the number of cells for which the P_CMAX is reported in the PHR payload by referencing the L field. Of course, it is possible to signal whether the P_CMAX exists by using the P bit in order to reduce complexity at the eNB. In this case, the eNB sets both the P bit and the V bit at step 645. Since the rest steps of the in the simplified UE procedure are identical with those described above, detailed description thereof is omitted herein.

With respect to a simplified eNB procedure, except for the following features, the simplified eNB procedure is identical with the procedure depicted in FIG. 7. That is, the eNB determines the P_CMAX for the cells for which the P_CMAX is not explicitly reported. If one P_CMAX is reported, then the eNB determines the P_CMAX for all the cells for which the V bit is set to 0 as the reported by the P_CMAX . If multiple P_CMAX information are reported, the eNB determines the P_CMAX reported in PH-reporting order of the cells for which the V bit is set to 0. The eNB determines the P_CMAX information for the cells for which the V bit is set to 1 as a predetermined value, e.g., P_{CMAX_H}. Since the rest of the steps simplified eNB procedure are identical to those described above, detailed description thereof is omitted herein.

FIG. 8 is a block diagram illustrating a configuration of a UE according to an exemplary embodiment of the present invention.

Referring to FIG. 8, the UE, according to the present exemplary embodiment, includes a transceiver 805, a controller 810, a multiplexer/demultiplexer 820, a control message processor 835, and a plurality higher layer devices 825 and 830.

The transceiver 805 receives data and control signals on a downlink carrier and transmits data and control signals on uplink carrier. In a case where multiple carriers are configured, the transceiver 805 can transmit/receive the data and control signals on multiple subcarriers.

The multiplexer/demultiplexer 820 multiplexes the data generated by the higher layer devices 825 and 830 and/or the control message processor 835 and outputs the multiplexed signal to the transceiver 805. The multiplexer/demultiplexer 820 also demultiplexes the data received by the transceiver 805 and delivers the demultiplexed data to the higher layer devices 825 and 830, the control message processor 835, and or/ the controller 810.

The control message processor 835 processes the control message transmitted via the network and takes an action in response to the control message. The control message processor 835 transfers a parameter (e.g., P_EMAX), which is included in the control message and which is necessary for determining P_CMAX , to the controller 810. The control message processor 835 also notifies the controller 810 of whether the REL-10 PHR is used.

The higher layer devices 825 and 830 are configured to be responsible for the respective services so as to process the data of user services, such as File Transfer Protocol (FTP) and VoIP, and deliver the processed data to the multiplexer/demultiplexer 820. The higher layer devices 825 and 830 process the data from the multiplexer/demultiplexer 820 and deliver the processed data to higher layer service applications.

The controller 810 analyses a scheduling command, e.g., an uplink grant, received through the transceiver 805 and controls the transceiver 805 and the multiplexer/demultiplexer 820 to perform uplink transmission using appropriate transmission resources at an appropriate time point. The controller 810 controls the P_CMAX reporting process when a predetermined condition is fulfilled. For example, if the PHR is triggered in a state where the REL-10 PHR function is activated, the controller 810 then starts the P_CMAX reporting process. At this time, the control unit 810 calculates the PHs for the cells in an active state and determines an arrangement order of the PHs in the payload of the PHR MAC CE. The controller 810 also determines the cells for which P_CMAX is to be reported from among the cells for which the PH is reported, and then sets the P bit of each PH to an appropriate value depending on whether the P_CMAX exists. The controller 810 transfers the payload of the PHR MAC CE to the multiplexer/demultiplexer 820.

Although not shown, the controller 801 includes a power calculator and a report processor. The power calculator calculates a PUSCH transmission power requested for each cell, determines a P_CMAX per cell for the PUSCH transmission, and calculates a PH per cell based on the difference between the PUSCH transmission power and the P_CMAX. The report processor generates the PHR MAC CE including the P_CMAX and the PH.

For this purpose, the report processor determines a position of each PH in the PHR MAC CE according to the priority order of the cells and places the PHs at their respective positions in the PHR MAC CE. The report processor also determines whether to encapsulate the P_CMAX of each cell in the PHR MAC CE and, if it is determined to encapsulate the P_CMAX of at least one cell, the report processor arranges the P_CMAX of the at least one cell so as to follow the PH in the PHR MAC CE. Here, the PHR MAC CE is configured per cell and includes fields for indicating whether the PH and the P_CMAX are carried and whether the PUSCH transmission occurs. The report processor also determines whether to perform the PUSCH transmission per cell and, if it is determined to perform the PUSCH transmission for at least one cell, encapsulates the P_CMAX for the at least one cell while excluding the P_CMAX for the rest cells.

FIG. 9 is a block diagram illustrating a configuration of an eNB according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the eNB includes a transceiver 905, a controller 910, a multiplexer/demultiplexer 920, a control message processor 935, a plurality of higher layer devices 925 and 930, and a scheduler 915.

The transceiver 905 transmits data and controls signals on a downlink carrier and receives data and control signals on an uplink carrier. In a case where multiple carriers are configured, the transceiver 905 can transmit/receive the data and control signals on the multiple carriers.

The multiplexer/demultiplexer 920 multiplexes the data generated by the higher layer devices 925 and 930 and/or the control message processor 935. The multiplexer/demultiplexer 920 also demultiplexes the data received from the transceiver 905 and delivers the demultiplexed data to the higher layer device 925 and 930, the control message processor 935, and/or the controller 910.

The control message processor 935 processes the control message transmitted by a UE and takes an action in response to the control message or generates a control message to be transmitted to a terminal, or UE, to lower layers of a communication protocol or lower layer devices. For example, the control message processor 935 transfers the P_PowerClass information transmitted by the UE to the controller 910.

The higher layer devices 925 and 930 are configured to be responsible for respective user services so as to process the data of the user services, such as FTP and VoIP, and delivers the processed data to the multiplexer/demultiplexer 920. The higher layer devices 925 and 930 process the data from the multiplexer/demultiplexer 920 and deliver the processed data to higher layer service applications.

The controller 910 processes the PHR MAC CE transmitted by the UE, and transfers scheduling-related information to the scheduler 915. For example, the controller 910 analyses the PHR received from the UE and notifies the scheduler 915 of the PH of the UE. The controller 910 determines the maximum transmission resource amount and coding rate available for the UE using the PH and the P_CMAX reported in the PHR and notifies the scheduler 915 of the determined values. The controller 910 controls the multiplexer/demultiplexer 920 in order to generate downlink data provided to the transceiver 905 according to the scheduling information provided by the scheduler 915.

If the PHR MAC CE is received from the UE, the control unit 910 analyzes the PHR MAC CE and determines the P_CMAX appropriate for the PUSCH transmission power of the UE and determines the PH for each cell according to the difference between the PUSCH transmission power and the P_CMAX of each cell. At this time, the controller 910 determines the position of the PH depending on priority order of the cells in the PHR MAC CE and checks the PH at the determined position. The controller 910 also determines whether the P_CMAX for each cell is included in the PHR MAC CE and, if P_CMAX for at least one cell is included, determines the P_CMAX. Alternatively, if no other P_CMAX for the remaining cells is included, the controller 910 determines the P_CMAX for the remaining cells according to the included P_CMAX. Here, the PHR MAC CE is configured on a per cell basis and includes information for indicating whether the PH and the P_CMAX are included and whether the PUSCH transmission occurs. If it is determined that there is no PUSCH transmission in at least one cell, the controller 910 uses a predetermined value for the cell having no PUSCH transmission as P_CMAX.

The scheduler 915 is responsible for allocating transmission resources to a UE in consideration of a buffer state, a channel state, and a power headroom state of the UE. The scheduler 915 controls the transceiver 905 so as to process the signal received from UE and in order to transit a signal to the UE. At this time, the scheduler 915 performs scheduling for the PUSCH transmission of the UE such that the PUSCH transmission power does not exceed the P_CMAX according to the PH.

FIG. 10 is a diagram illustrating a configuration of a PHR mace CE for use in an uplink scheduling method according to an exemplary embodiment of the present invention.

The exemplary embodiment of the present invention, as shown in FIG. 10, provides a method and apparatus for selecting a PHR format according the condition of the UE.

Referring to FIG. 10, if a REL-10 PHR is configured, the UE encapsulates the following information in a PHR MAC CE 1020. That is, the PHR MAC CE 1020 includes a bitmap 1025, a type 2 PH 1030 for the PCell, a type 1 PH 1040 for the PCell 1040, type 1 PHs 1050 and 1060 for the SCells, and P_CMAX information 1035, 1045, 1055, and 1065.

The bitmap 1025 is information indicating whether PH information for the SCell is included in the PHR MAC CE. The type 2 PH 1030 for PCell indicates the type 2 PH for the PCell. A Type 2 PH is the value obtained by subtracting the PUSCH transmission power and a Physical Uplink Control Channel (PUCCH) transmission power from the maximum transmission power. The Type 2 PH is for scheduling the PUSCH and the PUCCH transmissions of the UE. A type 1 PH is the value obtained by subtracting the PUSCH transmission power from the maximum transmission power. The type 1 PHs 1050 and 1060 for SCells are the type 1 PHs for SCells that are in an active state at a time when the PHR is generated. The PCMAX information 1035, 1045, 1055, and 1065 indicate the maximum transmission power used for calculating the PHs. Here, when the PHs are calculated with the PH calculation scheme 2, then the PCMAX information 1035, 1045, 1055, and 1065 can be omitted.

Furthermore, as shown in FIG. 10, a MAC sub header 1005 corresponding to the PHR MAC CE 1020 includes an LCID field 101 and an L field 1015, wherein the L field indicates a size of the PHR MAC CE 1020.

Referring to FIG. 10, the present invention is not limited thereto, and some of the information may unnecessary. For example, if no SCell is configured or the SCell is configured without an uplink for the UE while the REL-10 PHR is configured, then the uplink transmission of the UE occurs in the PCell, such that there is no need to report the type 1 PHs 1050 and 1060 for S Cells. Since there is no need to report the type 1 PHs 1050 and 1060 for SCells, it is also unnecessary to transmit the bitmap 1025. The length of a PHR MAC CE is variable according to a number of the type 1 PHs 1050 and 1060 for SCells that are reported. In a case where no type 1 PHs for SCells are reported, then the length of the PHR MAC CE is not variable, and thus the L field 1015 is not necessary in the MAC sub header 1005. The type 2 PH 1030 for PCell is used for when the UE can perform the PUSCH transmission and the PUCCH transmission simultaneously, and as such, it is only necessary for the simultaneous transmission of the PUSCH and the PUCCH transmissions.

The present exemplary embodiment of the present invention relates to the method for configuring the L field, the bitmap, and the type 2 PH for PCell selectively. That is, some of the fields depicted in FIG. 10, such as the L field, the bitmap field, and the type 2 PH field, are set depending on the situation.

FIG. 11 is a signaling diagram illustrating uplink signaling procedure between a UE and an eNB according to an exemplary embodiment of the present invention.

Referring to FIG. 11, the UE 1105 reports its capability information to the eNB 1110 through a predetermined RRC message signaling in step 1115. For example, the RRC message includes the information on whether the PUSCH and the PUCCH are transmitted simultaneously and the number of SCells that can be accumulated on a frequency band.

Next, the eNB 1110 configures the function related to the REL-10 PHR for the UE 1105 in consideration of the capability information and traffic condition of the UE 1105 and a load state of the cell. The eNB 1110 can transmit an RRC connection reconfiguration message to the UE 1105 in order to configure the SCell for the UE 1105 in step 1120. A SCell can be configured with only a downlink channel (hereinafter, such a cell is referred to as a downlink SCell) or both a downlink and an uplink channel (hereinafter, such a cell is referred to as a downlink/uplink SCell). If the UE 1105 operates mainly with the downlink traffic, the eNB 1110 assign a downlink SCell to the UE 1105. If the UE 1105 operates approximately equally with the downlink and uplink traffic, then the eNB 1110 assigns a downlink/uplink SCell to the UE 1105. The eNB 1110 also notifies the UE 1105 of whether the PUCCH/PUSCH parallel transmission is allowed for the UE 1105 and whether the REL-10 PHR is configured. The PUCCH/PUSCH parallel transmission is configured for the UE 1105 having a good channel condition from among UEs reported have the capability for the PUCCH/PUSCH parallel transmission.

The UE 1105 performs a connection reconfiguration according to an instruction in a RRC connection reconfiguration message. Afterward, if a PHR is triggered at a time point in step 1125, then the UE 1105 generates a PHR in step 1130 and transmit the PHR to the eNB 1110 in step 1135. At this time, the PHR format, which determines the fields to be included in PHR, is determined depending on whether the REL-10 PHR function is configured for the UE 1105, whether at least one SCell using an uplink channel is configured for the UE 1105, and whether the UE 1105 can perform the PUCCH/PUSCH parallel transmission. If the REL-10 PHR function is not configured for the UE 1105, then the UE 1105 encapsulates the type 1 PH for PCell in the PHR MAC CE. If the REL-10 PHR function is configured for the UE 1105, then the UE encapsulates the following information in addition to the type 1 PH and the P_CMAX for PCell in the PHR according to a situation or state of the UE 1105.

If a downlink/uplink SCell is configured and if the PUCCH/PUSCH parallel transmission is configured, then the UE 1105 enables the L field in the PHR MAC CE sub-header and the bit map, the type 2 PH for PCell, and the type 1 PHs for SCells in the PHR MAC CE. If the downlink/uplink SCell is configured and if the PUCCH/PUSCH parallel transmission is not configured, the UE 1105 enables the L field in the PHR MAC CE sub-header and the bit map and enables type 1 PHs for SCells in the PHR MAC CE. Whereas, if no downlink/uplink SCell is configured, and if the PUCCH/PUSCH parallel transmission is configured, then the UE 1105 disables the L field in the PHR MAC CE sub-header and enables the type 2 PH for PCell in the PHR MAC CE. If the downlink/uplink SCell is not configured and if the PUCCH/PUSCH parallel transmission is not configured, then the UE 1105 enables only the basic information fields of the PHR MAC CE sub-header and the PHR MAC CE.

That is, the UE 1105 determines whether to enable the L field and bitmap according to whether the downlink/uplink SCell is configured. The UE 1105 also determines whether to enable the type 2 PH for PCell according to whether the PUCCH/PUSCH parallel transmission is configured.

FIG. 12 is a flowchart illustrating a UE procedure for uplink scheduling method according to the second exemplary embodiment of the present invention.

Referring to FIG. 12, a UE configures the REL-10 PHR function in step 1205. The REL-10 PHR function is an extended PHR function, which differs from the REL-8 PHR function in format and type of information reported, and can be configured through RRC control message signaling for activating the REL-10 technology. Next, the UE waits until a PHR generation condition is fulfilled while performing a predetermined operation. The PHR generation condition is fulfilled when there are transmission resources available for a new uplink transmission, a timer restricting PHR transmission has expired or is currently running, and a path loss of at least one cell from among the cells fulfilling a predetermined condition changes to be over a predetermined threshold value.

Here, the cell fulfilling the PHR generation condition is a cell reporting the power headroom from among the cells in an active state, i.e., the SCell that is configured as a path loss reference cell of the PCell. The path loss reference cell is the cell that is referred to when calculating the uplink transmission power as specified in the 3GPP TSs 36.331 and 36.213.

Next, if the PHR is triggered at a certain time point, or in other words, if the PHR generation condition is met in step 1210, then the UE determines the information to be included in the PHR in step 1215. In other words, the UE determines whether an uplink SCell is configured at step 1215. If no downlink/uplink SCell is configured, or in other words, if a downlink SCell is configured for the UE, then the UE disables the L field in the PHR MAC CE sub-header and the bitmap in the PHR MAC CE, and the procedure goes to step 1230. If a downlink/uplink SCell is configured, then the procedure goes to step 1220.

At step 1220, the UE includes the L field in the MAC sub-header which indicates the length of the PHR MAC CE. The length of the PHR MAC CE is determined by a number of SCells supporting uplink transmission from among the SCells in an active state, a number of PCMAX information, and whether the type 2 PHs exist, at the time point when the PHR is generated. Next, the UE determines the SCells for which PHs are reported in the PHR, generates a bitmap in which the bits corresponding to the cell identifiers of the SCells are set to 1, and inserts the bitmap in the first byte of the PHR MAC CE in step 1225. Here, the bitmap is composed of 8 bits of which the most significant bit is used as a cell identifier 7, the next most significant bit is used as a cell identifier 6, and so one, wherein the least significant bit is used as a cell identifier 1. That is, the bit positions of the bitmap respectively correspond to the cell identifiers.

Next, the UE determines whether the PUCCH/PUSCH parallel transmission is configured in step 1230. If the PUCCH/PUSCH parallel transmission is configured, then the UE arranges the type 2 PHs for PCells in the first byte, when no bitmap exists, or the second byte, when the bitmap exists, of the PHR MAC CE in step 1235, and the procedure goes to step 1240. Otherwise, at step 1230, if it is determined that the PUCCH/PUSCH parallel transmission is not configured, then the procedure goes to step 1240. At step 1240, the UE generates the PHR MAC CE by inserting the type 1 PH for PCell and other necessary information, such as the P_CMAX and the type 1 PHs for the SCells when an active SCell supporting uplink transmission exists. Finally, the UE transmits the PHR MAC CE in step 1245.

The configuration of the UE according to the present exemplary embodiment of the present invention is similar to that as depicted in FIG. 8 except for the controller 810. The controller 810 of the UE according to the present embodiment of the present invention analyzes the scheduling command, i.e., the uplink grant, that is received through the transceiver 805 and controls the transceiver 805 and the multiplexer/demultiplexer 820 to perform uplink transmission on appropriate transmission resources at appropriate time points. If the PHR trigger condition is fulfilled, the controller 810 controls PHR procedure. In such a case, the controller 810 determines whether to include the L field, a bitmap, and type 2 PHs of PCells according to whether the downlink/uplink cell is configured and whether the PUCCH/PUSCH parallel transmission is configured. The controller 810 then generates the payload of PHR MAC CE, and transfers the payload of PHR MAC CE to the multiplexer/demultiplexer 820.

As described above, the uplink scheduling apparatus and method as described in the exemplary embodiments of the present invention is capable of reducing the power headroom report overhead, resulting in an improvement of eNB's scheduling efficiency and a reduction of interference with other uplink transmissions.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A method by a terminal in a wireless communication system, the method comprising:

receiving, from a base station, a radio resource control (RRC) message for configuring a power headroom report (PHR) for at least two cells;

identifying whether the PHR is triggered;

obtaining a power headroom (PH) based on a maximum transmission power and a physical uplink shared channel (pusch) power, when the PHR is triggered; and

transmitting the PHR including the PH and an indicator indicating whether the maximum transmission power is included in the PHR to the base station,

wherein a pusch reference format is used for the pusch power and the maximum transmission power is omitted in the PHR, when the PH is not based on a real transmission on a pusch.

2. The method of claim 1, wherein at least one of a first parameter related to a number of assigned transmission resources and a second parameter related to a modulation coding scheme (MCS) level are 0, when the pusch reference format is used for the pusch power.

3. The method of claim 1,

wherein the PHR is triggered, and

wherein, when a prohibit timer expires, a pathloss is changed more than a pathloss reference, and an uplink resource is configured.

4. The method of claim 1, wherein the PHR further includes the maximum transmission power used for obtaining the PH, when the PH is based on the real transmission on the pusch.

5. The method of claim 1, wherein the PHR comprises, when the PH is based on the real transmission on an uplink data channel, the maximum transmission power after the PH.

6. A terminal comprising:

a transceiver configured to transmit and receive a signal; and

a controller configured to:

receive, from a base station, a radio resource control (RRC) message for configuring a power headroom report (PHR) for at least two cells,

identify whether the PHR is triggered,

obtain a power headroom (PH) based on a maximum transmission power and a physical uplink shared channel (pusch) power, when the PHR is triggered, and

transmit the PHR including the PH and an indicator indicating whether the maximum transmission power is included in the PHR to the base station,

wherein a pusch reference format is used for the pusch power and the maximum transmission power is omitted in the PHR, when the PH is not based on a real transmission on a pusch.

7. The terminal of claim 6, wherein at least one of a first parameter related to a number of assigned transmission resources and a second parameter related to a modulation coding scheme (MCS) level are 0, when the pusch reference format is used for the pusch power.

8. The terminal of claim 6,

wherein the PHR is triggered, and

wherein, when a prohibit timer expires, a pathloss is changed more than a pathloss reference, and an uplink resource is configured.

9. The terminal of claim 6, wherein the PHR further includes the maximum transmission power used for obtaining the PH, when the PH is based on the real transmission on the pusch.

10. The terminal of claim 6, wherein the PHR comprises, when the PH is based on the real transmission on an uplink data channel, the maximum transmission power after the PH.

11. A method by a base station in a wireless communication system, the method comprising:

transmitting, to a terminal, a radio resource control (RRC) message for configuring a power headroom report (PHR) for at least two cells; and

receiving the PHR including a power headroom (PH) and an indicator indicating whether the maximum transmission power is included in the PHR from the terminal,

wherein a physical uplink shared channel (pusch) reference format is used for a pusch power and the maximum transmission power is omitted in the PHR, when the PH is not based on a real transmission on a pusch, and

wherein the PH is obtained based on the maximum transmission power and the pusch power, when the PHR is triggered.

12. The method of claim 11, wherein at least one of a first parameter related to a number of assigned transmission resources and a second parameter related to a modulation coding scheme (MCS) level are 0, when the pusch reference format is used for the pusch power.

13. The method of claim 11,

wherein the PHR is triggered, and

wherein, when a prohibit timer expires, a pathloss is changed more than a pathloss reference, and an uplink resource is configured.

14. The method of claim 11, wherein the PHR further includes the maximum transmission power used for obtaining the PH, when the PH is based on the real transmission on the pusch.

15. The method of claim 11, wherein the PHR comprises, when the PH is based on the real transmission on an uplink data channel, the maximum transmission power after the PH.

16. A base station comprising:

a transceiver configured to transmit and receive a signal; and

a controller configured to:

transmit, to a terminal, a radio resource control (RRC) message for configuring a power headroom report (PHR) for at least two cells, and

receive the PHR including a power headroom (PH) and an indicator indicating whether the maximum transmission power is included in the PHR from the terminal,

wherein a physical uplink shared channel (pusch) reference format is used for a pusch power and the maximum transmission power is omitted in the PHR, when the PH is not based on a real transmission on a pusch, and

wherein the PH is obtained based on the maximum transmission power and the pusch power, when the PHR is triggered.

17. The base station of claim 16, wherein at least one of a first parameter related to a number of assigned transmission resources and a second parameter related to a modulation coding scheme (MCS) level are 0, when the pusch reference format is used for the pusch power.

18. The base station of claim 16,

wherein the PHR is triggered, and

wherein, when a prohibit timer expires, a pathloss is changed more than a pathloss reference, and an uplink resource is configured.

19. The base station of claim 16, wherein the PHR further includes the maximum transmission power used for obtaining the PH, when the PH is based on the real transmission on the pusch.

20. The base station of claim 16, wherein the PHR comprises, when the PH is based on the real transmission on an uplink data channel, the maximum transmission power after the PH.